1. Field of the Invention
The present invention relates to oxyalkylated polyglycerols and water-based lubricants prepared therefrom. These lubricants have excellent shear strength stability.
2. Description of the Prior Art
It is known to oxyalkylate glycerol, and U.S. Pat. No. 2,733,272 discloses oxyalkylating glycerol with mixtures of ethylene oxide and propylene oxide. The ratio of ethylene oxide to propylene oxide is 20:80 to 80:20 with 1:1 being preferred and a very broad area of use is specified. However, the molecular weight range is a maximum of 5,000 to 6,000 which is way below the desired value for the thickening agents of the present invention. In addition, the glycerol base does not provide the advantages obtained by polyglycerol bases.
It is also known to oxyalkylate polyglycerols such as diglycerols and triglycerols. For example, U.S. Pat. No. 3,110,737 discloses oxyalkylating with a mixture of butylene oxide and ethylene oxide, and U.S. Pat. No. 2,679,520 shows oxypropylating lower polyglycerols and then making esters therefrom. In both cases, the higher polyglycerols are rejected, and the patentees are making water-insoluble products. Therefore, the patentee's products are not suitable as thickening agents for hydrolubes.